（加试题）有如下程序段：

Dim i As Integer, Sum As Integer

Dim a(1 To 11) As Integer

Sum = 6

a(11) = 49

For i = 10 To 1 Step -1

    a(i) = a(i + 1) - 1

    If a(i) Mod 3 = 0 Then Sum = Sum + a(i)

Next i

Text1.Text = Str(Sum)

该程序段运行后，文本框text1中显示的内容是（   ）

A、174

B、180

C、36

D、42